The increasing number of financial and personal transactions being performed on local or remote microcomputers has given impetus for the establishment of “trusted” or “secured” microprocessor environments. The problem these environments try to solve is that of loss of privacy, or data being corrupted or abused. Users do not want their private data made public. They also do not want their data altered or used in inappropriate transactions. Examples of these include unintentional release of medical records or electronic theft of funds from an on-line bank or other depository. Similarly, content providers seek to protect digital content (for example, music, other audio, video, or other types of data in general) from being copied without authorization.
One component of such a trusted microprocessor system may be a trusted platform module (TPM), as disclosed in the Trusted Computing Platform Alliance (TCPA) Main Specification, version 1. 1a,1 Dec. 1, 2001, issued by the Trusted Computing Platform Alliance (available at www.trustedpc.com at the time of filing of the present application). The TPM may include several special registers, called platform configuration registers (PCR). The PCRs may be used to store encrypted digests of files, including software programs, which may later be retrieved to further the process of authentication. As the contents of these PCRs are therefore significant to the secure or trusted nature of the system, the PCRs should not be reset by general-purpose operations of the system. Current design limits the PCRs to be reset only upon a general system reset (e.g. power-on reset).